While theft of mail is rare, U.S. Postal Service officials say no one should send cash through the mail because its theft is not able to be tracked easily. If a gift card, money order or personal check is stolen, its redemption can be traced.(Photo: Andrew Harrer, Getty Images)

It was not immediately known how many gift cards weren't delivered and the amount stolen.

At least three other mail carriers in recent months have pleaded guilty to similar crimes:

• On Nov. 27, Sonte E. Gibbons, 25, of Cleveland, was sentenced to six months in prison for stealing gift cards on his route in the suburbs of Eastlake and Willowick, Ohio.

On April 13, 2017, Gibbons was supposed to deliver a letter containing a Walmart gift card but instead redeemed it three days later while wearing his postal uniform, according to the U.S. Postal Service's Office of Inspector General. When more people along his route complained of not receiving expected mail, postal agents prepared 10 greeting cards containing gift cards and mailed them; seven of the 10 were not delivered.

• On Sept. 12, Ebony Lavonne Smith, 20, of Milwaukee pleaded guilty to stealing more than 6,000 greeting cards filled with cash and checks sent to the Milwaukee suburb of Wauwatosa, Wisconsin. She is scheduled to be sentenced Feb. 8, according to court documents filed Oct. 31.

The mail carrier had been observed rifling through trays assigned to other delivery routes, removing greeting cards and placing them in her tray. When she was caught with a test greeting card that contained a transmitter, authorities also found more than 50 other greeting cards set aside in her vehicle, and it was later determined that she had been taking envelopes from March 3, 2017, to Jan. 3 of this year.

• On Sept. 18, 2017, a mail carrier in Sheridan County, Kansas, about halfway between Kansas City and Denver, was sentenced to six months in prison and ordered to pay $4,000 in restitution.

James Stephenson, then 25, of Hoxie, Kansas, pleaded guilty to one count of mail theft and said that he looked for birthday and anniversary cards likely to contain cash, gift cards and prepaid debit cards that he took for his own use, said the U.S. Attorney's Office for the Northern District of Ohio.

Don't send cash through the mail because its theft is not able to be tracked, postal officials said. Gift cards, money orders and personal checks have the ability to be traced when cashed.